EMT/QIS: Quantum Control of Impurity States in a Semiconductor

Michigan State University, East Lansing MI

Investigators

Abstract

Quantum Control of Impurity States in a Semiconductor Brage Golding and Mark Dykman Michigan State University E. Lansing, MI 48824 ABSTRACT Quantum information is a new and rapidly developing interdisciplinary area of research that resides at the interface between quantum physics and information science. It addresses some of the most challenging fundamental problems in science and technology while seeking to advance our understanding of the unique properties of the quantum world. Among the predictions in this field is that of an exponential speedup of computers that operate on purely quantum principles. If quantum properties are to be exploited for qualitatively new capabilities, it is necessary to build systems that exhibit long-lived, controllable quantum states. In addition, the devices should be compatible with conventional electronics and photonics. The devices based on controlled impurity states in semiconductors stand out as particularly attractive, since they should be scalable, operate at high speed, and take advantage of existing semiconductor technology. The quantum systems studied in this experimental and theoretical research are based on acceptors in a semiconductor such as silicon. These are substitutional dopants, whose atomic-like properties are well-known and invariant. The two states of a qubit are the lowest orbital states of the acceptor, a result of splitting of the ground state by strain and electric field. The distance between the energy levels is in the range of a few GHz and each qubit is individually controlled by a gate electrode. Single-qubit operations can be performed with short microwave pulses whereas two-qubit operations are enabled by the long-range dipolar interaction between the acceptors, which allows the qubit-qubit distance to be more than 100 nm. The readout of the final state of the system is based on quantum nondemolition optical measurement of light scattering by an exciton bound to the acceptor.